Blowpipe tests

Ldtrohr-flamme, /. blowpipe flame, -fluss, m. blowpipe flux. -gebl e, n. blast lamp, -kapelle, /. blowpipe cupel, -kohle, /. blowpipe charcoal, -lampe, /. blowpipe lamp, -probe,/, blowpipe teat, -priifgeratschaft,/. apparatiis for blowpipe testing, -reagens, n. blowpipe reagent, -versuch, m. blowpipe experiment or test. 

Lflt-versuch, m. blowpipe test soldering test, -wasser, n. soldering fluid, -zinn, n. soldering tin. 

Detection.—Dry Tests.—Salts of cobalt are usually of a rose-red colour when hydrated, and yield a beautiful blue colour in the borax bead test provided they are not present in excessive amount, otherwise the bead becomes opaque and appears black. When heated on charcoal with reduction mixture in the blowpipe test, metallic cobalt separates out in the form of small magnetic beads. When strongly heated with alumina a blue colour is produced, known as Thenard s blue. 

Dry tests a. Blowpipe test. When a lead salt is heated with alkali carbonate upon charcoal, a malleable bead of lead, (which is soft and will mark paper), surrounded with a yellow incrustation of lead monoxide is obtained. 

Dry test (blowpipe test) When a silver salt is heated with alkali carbonate on charcoal, a white malleable bead without an incrustation of the oxide results this is readily soluble in nitric acid. The solution is immediately precipitated by dilute hydrochloric acid, but not by very dilute sulphuric acid (difference from lead). 

Dry test (blowpipe test). When a bismuth compound is heated on charcoal with sodium carbonate in the blowpipe flame, a brittle bead of metal, surrounded by a yellow incrustation of the oxide, is obtained. 

Dry tests a. Blowpipe test All cadmium compounds when heated with alkali carbonate on charcoal give a brown incrustation of cadmium oxide CdO. 

Dry tests a. Blowpipe test All tin compounds when heated with sodium carbonate, preferably in the presence of potassium cyanide, on charcoal give white, malleable and metallic globules of tin which do not mark paper. Part of the metal is oxidized to tin(IV) oxide, especially on strong heating, which forms a white incrustation upon the charcoal. 

Dry tests a. Blowpipe test When iron compounds are heated on charcoal with sodium carbonate, grey metallic particles of iron are produced these are ordinarily difficult to see, but can be separated from the charcoal by means of a magnet. 

II. Dry tests (blowpipe test) Aluminium compounds when heated with sodium carbonate upon charcoal in the blowpipe flame give a white infusible solid, which glows when hot. If the residue be moistened with one or two drops of cobalt nitrate solution and again heated, a blue infusible mass (Thenard s blue, or cobalt meta-aluminate) is obtained. It is important not to use excess cobalt nitrate solution since this yields black cobalt oxide Co304 upon ignition, which masks the colour of the Thenard s blue. 

Dry tests a. Blowpipe test All cobalt compounds when ignited with sodium carbonate on charcoal give grey, slightly metallic beads of cobalt. If these are removed, placed upon filter paper, and dissolved by the addition of a few drops of dilute nitric acid, a few drops of concentrated hydrochloric acid added and the filter paper dried, the latter is coloured blue by the cobalt chloride produced. 

Dry tests (blowpipe test) Compounds of zinc when heated upon charcoal with sodium carbonate yield an incrustation of the oxide, which is yellow when hot and white when cold. The metal cannot be isolated owing to its volatility and subsequent oxidation. If the incrustation is moistened with a drop of cobalt... 

Dry test (blowpipe test) when antimony compounds are heated with sodium carbonate upon charcoal, a brittle metallic bead, surrounded by a white incrustation, is obtained. 

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Mineral identification is also sometimes possible on the basis of specific physical characteristics such as density, hardness, streak, or by flame coloration tests, microcosmic bead colors, or blowpipe tests. These methods are seldom of general applicability, but they may be useful in particular circumstances. 

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